var fath=document.getElementsByClassName("ygxq")[0];
var lis = fath.getElementsByTagName("li");
var divs=document.getElementsByClassName("bot");

for(var i=0;i<lis.length;i++){
    lis[i].onclick=function(){

        for(var i=0;i<lis.length;i++){
            lis[i].className="";
            divs[i].className="bot";
        }
        this.className="active2";
        var index=parseInt(this.getAttribute("xh"));
        divs[index].className="bot active1";
    }
}